3,587 research outputs found

    The decays "neutrino{heavy} -> neutrino{light} + photon" and "neutrino{heavy} -> neutrino{light} e+ e-" of massive neutrinos

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    If, as recently reported by the Super-Kamiokande collaboration, the neutrinos are massive, the heaviest one would not be stable and, though chargeless, could in particular decay into a lighter neutrino and a photon by quantum loop effects. The corresponding rate is computed in the standard model with massive Dirac neutrinos as a function of the neutrino masses and mixing angles. The lifetime of the decaying neutrino is estimated to be approximately 10^44 years for a mass 5 10^{-2} eV. If kinematically possible, the decay of a heavy neutrino into a lighter one plus an e+ e- pair occurs at tree level and its one-loop radiative corrections get enhanced by a large logarithm of the electron mass acting as an infrared cutoff. It then largely dominates the photonic mode by several orders of magnitude, corresponding to a lifetime approximately equal to 10^{-2} year for a mass 1.1 MeV.Comment: 12 pages, LaTeX 2e (epsf) with 9 postscript figures and one logo. Some comments and references adde

    Contribution of higher nucleon resonances to K*{\Lambda} photoproduction

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    We investigate K*{\Lambda}(1116) photoproduction off the proton and neutron targets in the effective Lagrangian method in the tree-level Born approximation. In addition to the K, K*, and {\kappa} exchanges which are the main contributions to the reaction, we consider the contributions from the higher nucleon resonances D13(2080) and the D15(2200). We find that the D13(2080) plays a crucial role in explaining the enhancement of the near-threshold production rate, which results in a good agreement with the experimental data for the proton targets, while the contribution of the D15(2200) is rather small. A similar conclusion is drawn for K* photoproduction off the neutron targets. In addition to the energy and angular dependence of the cross sections, we present the predictions on the photon-beam asymmetry.Comment: 12 pages, 19 figure

    Genotyping via Amplification and Hhal Cleavage of Apolipoprotein E (ApoE) Gene in Patients with Coronary Artery Disease

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    DNA amplification and HhaI cleavage for the apolipoprotein E (apofi) genotyping is identified in 108 patients with coronary artery disease (CAD). A group of randomly selected 100 normal individuals analysed as control samples. There were no significant differences in apoE genotype frequencies between the two groups. Analysis of variances was performed to test for mean differences in plasma lipids. lipoprotein and apolipoprotein B (apoB) levels. Compared to controls, patients with CAD had significantly higher levels of total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-ChoI). The ratios of LDL-Chol to apoB were also elevated in the CAD group. The levels of TC and LDL-Chol in the E3j3 genotype of patients were significantly higher than those of the controls. The high density Iipoprotein-cholesteroI(HDL-ChoI) levels in E4j3 type of the patients were significantly higher than those of E3j3 subjects. As phenotype analysis for the apoE polymorphism differs somewhat among populations, so we discussed possible reasons for these discrepancies

    The Rank four Heterotic Modular Invariant Partition Functions

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    In this paper, we develop several general techniques to investigate modular invariants of conformal field theories whose algebras of the holomorphic and anti-holomorphic sectors are different. As an application, we find all such ``heterotic'' WZNW physical invariants of (horizontal) rank four: there are exactly seven of these, two of which seem to be new. Previously, only those of rank 3\le 3 have been completely classified. We also find all physical modular invariants for su(2)k1×su(2)k2su(2)_{k_1}\times su(2)_{k_2}, for 22>k1>k222>k_1>k_2, and k1=28k_1=28, k2<22k_2<22, completing the classification of ref.{} \SUSU.Comment: 25 pp., plain te

    A MATLAB based simulation program for indoor visible light communication system

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    We report a simulation program for indoor visible light communication environment based on MATLAB and Simulink. The program considers the positions of the transmitters and the reflections at each wall. For visible light communication environment, the illumination light-emitting diode is used not only as a lighting device, but also as a communication device. Using the simulation program, the distributions of illuminance and root-mean-square delay spread are analyzed at bottom surface
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